The present invention relates generally to a mobile hay stack-forming machine and more particularly to a control mechanism for opening and closing the door on such a machine.
It is old in the art for stack wagons having vertically reciprocable roofs to utilize the roof movement to unlatch and open and then close and latch their stack discharge doors. See, for example, the U.S. Pat. No. 3,901,142, granted Aug. 26, 1975 and assigned to Deere & Company, wherein both latch movement and door movement are controlled by compressor roof movement. Other examples wherein latch movement is manually controlled and door movement is dependent upon roof movement are disclosed in U.S. Pat. No. 3,691,741 issued Sept. 19, 1972 to White et al., and U.S. Pat. No. 3,732,672 issued May 15, 1973 to Adee et al.
When a door latch must be manually released after a stack has been formed, the back pressure on the door exerted by the compressed stack often makes unlatching extremely difficult. When the unlatching control is integrally part of the door opening control, then failure of the latch to release can cause substantial damage to both the door and the crop-receiving body as the door opening control attempts to open a latched door.
An additional problem encountered with mechanical unlatching and door opening mechanisms similar to those available in the prior art arises as a result of the dust, dirt and foreign matter which accumulates in the springs, housing and channels of the mechanism. Manual unlatching and latching become difficult if not impossible unless this material is removed and unlatching even by mechanical means can be unreliable due to the compressed stack back pressure and foreign matter interference with latch clearances.
Accordingly, applicant has provided a door control mechansim which is neither manually unlatched nor latched, and is not dependently coupled with another operation of the stack wagon cycle. Neither does applicant's unlatching mechansim contain any channels, nor other dust and dirt gathering recesses which would fill with foreign matter to retard unlatching operation. In this manner, applicant has provided for positive opening of the latch prior to opening of the door and for opening of the door independently of roof position or movement.